Cabin Pressurization

One of those who participated in the Flight without Fear program said that one of the reasons for her anxiety is the fear that the air on the plane will end. In particular, she was afraid when the plane was delayed before takeoff, fearing that at that time they were breathing the oxygen that would be needed for passengers on the flight. Obviously, she didn’t know about Cabin Pressurization

This is one example of many that explains why knowledge is power. After a ten-minute explanation, she realized that this fear was not based on reality.

So for all those who are afraid like that participant, or those whose safety video terrifies them, let us detail the air pressure in the plane, the oxygen we breathe, and – what happens when there are disruptions.

Some Theory

Air composition in the atmosphere is constant. Each unit of air volume has about 20% oxygen, and the rest of the air, mostly consists of nitrogen.
We need oxygen, and in each breath, we need a certain amount of oxygen. Lack of oxygen causes a phenomenon called hypoxia, and depending on the severity of the distress caused by lack of oxygen, we lose consciousness quickly, and if we do not receive oxygen on time, we die.

A physical law states that although the percentage of oxygen remains constant in all la

Want to know more about Cabin Pressurization?
Want to know more about Cabin Pressurization?

yers of the atmosphere, the amount of oxygen in each volume unit decreases when the air pressure decreases. As altitude rises, air pressure drops. In the high mountains it is known that the air is thin, and at very high altitudes, such as those where passenger planes fly, the air is thin enough to survive.

Cabin Pressurization in Airplanes

To maintain the passengers, the fuselage is compressed by air from the outside, which is compressed in the aircraft engines, thus maintaining proper pressure allowing free breathing in the aircraft.
In order for the aircraft not to be compressed to infinity, a special valve in the tail of the plane releases the air in a controlled manner and maintains the desired pressure.
You can understand that the air on board the plane is simply external air. It cannot be finished, it is very clean of soot, pollution, dust, and bacteria and after a short stay in the plane, it is released to the atmosphere.

Cabin Pressurization scheme in airplanes
Cabin Pressurization scheme in airplanes

Like any critical system in passenger aircraft, the air compression system is made up of several independent components, so that failure in one of them will not cause the air pressure to fall. But what happens if a failure in the structure of the plane causes the pressure to escape?
Such breakdowns are rare, and one of the worst known to us recently occurred on April 17, 2018.  The disintegration of part of a US 737 aircraft engine caused part of the engine to fly toward the fuselage, to tear a hole in the side of the plane through which it was sucked out. Although the passengers pulled her in she died, apparently from exposure. Extreme cold and oxygen deprivation. The rest of the passengers, wearing the oxygen masks, were unharmed.

What happens when the pressure drops in flight?

A case in which an opening is opened in the passenger compartment is very rare. The fall of pressure can happen for other reasons, and the plane is built to provide a solution that will allow all passengers to reach the ground safely.
Over each group of seats on the plane is installed an automatic system, which is used to decrease pressure. Oxygen masks are then released in a larger number than those in the same group of seats. These masks allow each passenger to receive sufficient oxygen until the plane reaches a lower altitude where air can be breathed under sufficient pressure. It happens at 10,000 feet, about 3 miles.

In case the aircraft pressurization drops, use the masks
In case the aircraft pressurization drops, use the masks

In case the plane’s air pressure actually falls, and the masks are released, the most important thing is to wear a mask, first of all, your own and then to help the others near you. Every second counts, and if you faint from lack of oxygen you will not be able to help others.
If a case like this happens to you when you are not in your seat, at the crossing, for example, reach out and grab a mask from one of your sides.

Want to know more about Cabin Pressurization
Want to know more about Cabin Pressurization?

Remember that above each group of seats, there is usually one additional mask.
The toilet also has an oxygen mask. Most important to wear a mask, we said already … right?
At the same time, the pilots will begin the emergency descent, and you will feel that the plane is going down. This descent may also be accompanied by vibration caused by the speed brakes, which are surfaces that rise above the wing and help to lose altitude quickly.
This can take about ten minutes, and at the end, the passengers and crew will be able to remover their masks.

Summary Cabin Pressurization

The air that breathes in the passenger compartment comes from the outside
It is compressed and heated to the required conditions
The air in the plane changes at a high rate
In case of pressure drop in the plane, it is most important to wear an oxygen mask

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